Electronic packages which utilize thin flexible circuit members as part thereof are known in the industry, with examples being defined in U.S. Pat. Nos. 4,849,856, 4,914,551 and 4,937,707, all of which are assigned to the same assignee as the present invention. Understandably, a main objective in the design of such electronic packages is to provide a maximum number of electrical connections within a minimum of overall space. Such miniaturization efforts, while providing highly advantageous features, also present various engineering problems in both the manufacture and ultimate operation of these structures. One example of such a problem involves effective package heat removal during operation, such removal provided by the structures defined in the aforementioned U.S. Pat. Nos. 4,849,856 and 4,914,551.
Another particular problem facing designers of electronic packages containing thin film circuit structures is the essential requirement to provide sound and effective electrical connections between relatively large numbers of extremely small conductive elements (e.g., signal, ground and/or power conductors) on the flexible circuit and the respective contact locations (e.g., those conductors located on the printed circuit board or similar substrate) to which the flexible circuit is to be electrically connected, thus coupling the chip to the package's substrate. Typically, such flexible circuit-to-substrate connections have been made in most electronic packages of this type using solder or similar bonding material to thus form a substantially permanent connection. While soldering or similar techniques (e.g., thermocompression bonding) have proven successful to provide such connections, including at relatively high densities, such processes understandably add to the cost and time involved for manufacturing such structures. Further, because the resulting structure is substantially permanently attached at these locations, separability (e.g., as may be required during periods of repair) is virtually impossible. Accordingly, repair and/or replacement can prove to be relatively expensive and time-consuming.
In U.S. Pat. No. 4,597,617, there is shown an electronic package wherein a flexible circuit is utilized and connected to circuitry on the package's substrate (etched circuit board) without permanent attachment (e.g., soldering). Because the flexible circuit as described in this patent is maintained in relatively fixed alignment with respect to the package's retainer and associated heat sink members in the manner described, however, this package is not capable of providing high density electrical connections (e.g., between associated arrays of individual conductors located in closely spaced orientations) such as taught by the present invention. Further, use of a substantially singular elastomeric pressure pad for each side of the flexible circuit, as described in U.S. Pat. No. 4,597,617, does not provide the unique force application per individual circuit conductor as required in highly dense arrays (and as provided by the instant invention) and deemed necessary to assure high density connections between conductors as provided on flexible circuits and corresponding printed circuit boards or the like.
The invention, as defined herein, is capable of providing high density connections between individual conductor pads or the like arranged on the flexible circuit in a high density pattern with corresponding pads or the like on an associated substrate (e.g., printed circuit board) in both an expeditious and effective manner which, uniquely, also assures separability of the various parts of the final package in a facile manner to thus facilitate replacement and/or repair.
It is believed that an electronic package assembly possessing the several advantages specifically described herein and otherwise discernible from these teachings would constitute a significant advancement in the art.